There is a growing need for heated seat cushions and backrests for outdoor and/or cold-weather venue seating environments such as stadiums, amphitheaters, and municipality seating venues such as parks and public transit areas. Also, there is increased demand for safe, inexpensively-powered heated cushions for outdoor recreation activities such as hunting, fishing, and operating ATV's, UTV's, etc. A known seat cushion/backrest heating system uses a fixed wattage method of providing conductive heat to the user. Generally, a fixed resistance heater is inserted into the seat and/or backrest cushion upon which the occupant will sit. This heater can be a stitched wire, carbon fiber, or an etched heater pad. These heating systems usually have a single point temperature feedback loop or a thermostat shutoff. The fixed resistance heaters have a constant current draw during operation of the heater.
There are several disadvantages for these types of fixed resistance seat heating systems. All of these fixed resistance systems have a failure mode which could be hazardous to the user. Use of a fixed resistance heater requires a sensing device, such as a thermostat, to control the temperature. This method of temperature sensing measures the temperature of a single point on the heater and assumes that the rest of the heater is operating at the same temperature. In the event this sensing device malfunctions, or if the temperature increases in other areas of the heater outside of the sensor, the heating device could produce a hazardous condition to the user.
Another challenge is providing an inexpensive method to provide renewable power to these heaters in cold environments over extended periods of time. Battery life, size, portability and durability are all major considerations to cost-effectively provide continuous power to these heated devices.